INSM files Form 144 for proposed Common share sales

INSM submitted a Form 144 reporting proposed sales of Common stock.

Rhea-AI Filing Summary

INSM submitted a Form 144 reporting proposed sales of Common stock. The filing, dated 05/04/2026, lists multiple sale entries by William Lewis with transaction dates from 02/03/2026 through 04/16/2026. The entries are recorded under "Stock Plan Activity" and identify Common shares to be sold on NASDAQ.

Insights

Securities Compliance Counsel

Form 144 is a statutory notice of proposed insider resale under Rule 144.

Form 144 provides a public notice that an affiliate or control person intends to sell restricted or control securities; it does not itself report completed trades. The filing lists multiple dated entries and identifies the selling person as William Lewis.

Timing and actual sale execution are not confirmed here; subsequent Form 4 or broker reports would show completed transactions if they occurred.

Key Figures

Filing date: 05/04/2026 Sale entry range: 02/03/2026–04/16/2026 Number of dated entries listed: 7 entries +1 more

4 metrics

Filing date 05/04/2026 Form 144 filing date shown on the excerpt

Sale entry range 02/03/2026–04/16/2026 Transaction dates listed for William Lewis' entries

Number of dated entries listed 7 entries Seven dated sale lines for William Lewis appear between 02/03/2026 and 04/16/2026

Exchange NASDAQ Exchange identified for the Common stock in the filing

Key Terms

Form 144, Stock Plan Activity, Rule 144

3 terms

Form 144 regulatory

"144: Securities To Be Sold"

Form 144 is a document that investors must file with the government when they plan to sell a large number of shares of a company's stock. It helps ensure transparency so everyone knows how many shares are being sold and when, which can impact the stock's price.

Stock Plan Activity financial

"Common | 05/04/2026 | Stock Plan Activity"

Rule 144 regulatory

"144: Securities To Be Sold"

Rule 144 is a U.S. securities regulation that sets conditions under which restricted or insider-held shares can be legally resold to the public, such as required holding periods, availability of public information, limits on how much can be sold at once, and certain filing requirements. For investors it matters because it determines when previously locked-up shares can enter the market — like a release valve that can increase supply, affect share price, and signal insider intent.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What does the INSM Form 144 report?

The Form 144 reports proposed sales of Common stock by an affiliate. It lists multiple sale entries and identifies the selling person as William Lewis, with dates ranging from 02/03/2026 to 04/16/2026.

When was the INSM Form 144 filed?

The filing is dated 05/04/2026. That date appears at the top of the excerpt and anchors the reported stock plan activity and sale entries listed in the form.

Who is listed as the selling person in INSM's filing?

The excerpt names William Lewis with an address in Bridgewater, NJ. Multiple entries attribute proposed Common stock sales to that individual on various dates in 2026.

Does Form 144 confirm completed share sales for INSM?

No. Form 144 is a notice of proposed resale under Rule 144 and does not itself confirm completed trades. Execution details would appear in subsequent trade reports or Form 4 filings if sales occurred.

What exchange is referenced in the INSM filing?

The excerpt identifies NASDAQ as the market for the Common stock referenced in the Form 144 entries and the filing date line.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 05/04/2026 - 04:55 PM EDT Learn about SEC filing dates

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001402051
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	INSMED INC
SEC File Number	000-30739
Address of Issuer	700 US Highway 202/206 Bridgewater NEW JERSEY 08807
Phone	9089779900
Name of Person for Whose Account the Securities are To Be Sold	William Lewis
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Officer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common	Merrill Lynch 1800 K ST NW Suite 800 Washington DC 20006	10699	1469481	215551896	05/04/2026	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common	05/04/2026	Stock Plan Activity	Issuer			10699	05/04/2026	n/a

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	04/16/2026	10699	1540292
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	04/06/2026	10699	1746319
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	03/19/2026	10699	1535514
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	03/05/2026	10699	1562311
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	02/19/2026	10699	1615250
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	02/09/2026	13396	1979774
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	02/03/2026	3009	470412

144: Remarks and Signature

Remarks
Date of Notice	05/04/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	09/04/2025
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	William Lewis
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)